Injection-moulded article and process for the production thereof

Abstract

The invention relates to new injection-moulded articles made from metal/plastic composite systems containing a polyurethane adhesive (intermediate) layer, and a process for the preparation thereof.

We claim: 
     
       1. A process for preparing an injection molded article which is a metal/plastic composite bonded with a tack-free polyurethane adhesion promoter layer, said process consisting essentially of first applying polyurethane adhesion promoter to metal thereby forming a layer having a thickness of 2 to 80 μ, secondly, drying the promoter layer wherein the promoter layer is formed from (1) a polyurethane solution based on polybutylene adipate or polybutylene hexylene adipate having a molecular weight of 1000 to 8000 and hexamethylene diisocyanate or (2) a polyurethane dispersion based on a polyalkylene adipate or polyalkylene phthalate having a molecular weight of 1000 to 8000 and tolylene diisocyanate or hexamethylene diisocyanate, then thirdly encapsulating the promoter-layered metal by injection molding with a thermoplastic composition based on cellulose ester, polyvinyl chloride, polyamide, polycarbonate, polysulphone, ABS, polymethyl methacrylate, polyphenylene sulphide, polyalkylene terephthalate, polyarylene terephthalate, polyphenylene oxide, polyphosphonate or polyether ester ketone. 
     
     
       2. A process according to claim 1, wherein the polyurethane adhesion promoting layer is applied to shaped metal articles by dip-coating, knife-coating or pressure-coating. 
     
     
       3. A process according to claim 1 wherein the layer has a thickness of 15 to 30 μm. 
     
     
       4. A process according to claim 1 wherein the polyurethane adhesion promoter layer is formed from a polyurethane solution based on polybutylene adipate or polybutylene hexylene adipate having a molecular weight of 1000 to 8000 and hexamethylene diisocyanate. 
     
     
       5. A process according to claim 1 wherein the polyurethane adhesion promoter layer is formed from a polyurethane dispersion based on the polyalkylene adipate or polyalkylene phthalate having a molecular weight of 1000 to 8000 and tolylene diisocyanate or hexamethylene diisocyanate. 
     
     
       6. A process according to claim 5 wherein the polyurethane adhesion promoter layer contains aliphatic diamines. 
     
     
       7. A process according to claim 5 wherein the polyalkylene adipate or polyalkylene phthalate has a molecular weight of approximately 2000. 
     
     
       8. A process according to claim 1 wherein the promoter layer is applied to the metal by dipcoating or pressure coating. 
     
     
       9. A process according to claim 8 wherein the layer has a thickness of 15 to 30 μm. 
     
     
       10. A process according to claim 8 wherein the polyurethane adhesion promoter layer is formed from a polyurethane dispersion based on a polyalkylene adipate or polyalkylene phthalate having a molecular weight of 1000 to 8000 and tolylene diisocyanate or hexamethylene diisocyanate.